Synthetic linear polycarbonamides



Patented Mar. 15, 1949 UNITED STATES PATENT OFFICE SYNTHETIC LINEAR POLYCARBONAMIDES William Kirk, Jr., and Richard Seyfarth Schreiber, Wilmington, DeL, asslgnors to E. I. du Pont de Nemours & Company, Wilmington, Del., a

corporation of Delaware No Drawing. Application April 3, 1945, Serial'No. 586,447

This invention relates to polyamides and more particularly to fiber-forming synthetic linear polyamides.

Linear fiber-forming v synthetic polyamides (nylons) of the type discussed in U. S. Patents 2 Claims. (01. 260-78) in which R and Ar have the values previously indicated. Thus, interpolyamides in which a substantial amount of the above compounds may beemployed include, for example, those resulting from the condensation of the above type of di- 2,071,250, 2,071,251 and 2,130,948 have great util- 5 amine with a dibasic acid in the presence of minor ity particularly in the production of filaments by amounts of a polymerizablelactam such as capromelt spinning for use in fabrics. Such polylactam, or minor amounts of other polyamideamides are not soluble in the usual organic solforming diamines. These polyamides are obvents and the preparation of-films from such tained by the reaction of linear polymer-forming polymers is diflicult." While these polyamides do compositions containing bifunctional groups not absorb water to the extent that cupramwhich are complementary to reactive amide- ,monium and viscose rayons do, they do absorb forming groups in other molecules. On hydrolywater to an extent (usually above 5%) which is sis by dilute acids such as dilute hydrochloric undesirable for some. purposes, and do not have acid, there are obtained from the polyamides of the stiffness or transparency which are desirable this invention substantial amounts of the acid for certain applications. Certain interpoly- [salts of the diamines of the formula previously amides which have been previously prepared and given and at least one dicarboxylic acid. From which are sufficiently soluble to be employed in interpolyamides there may be obtained salts of I the casting of film from certain solutions have a other diamines and other dicarboxylic acids.

very, high water absorption and relatively low A preferred method of obtaining the polystiffness, especially when wet. These polymers amides of this invention consists in mixing essenare accordinglynot preferred for many applicatially molecular equivalent amounts of a dibasic tions involving fllmsor fibers. acid and the above-mentioned type of diamine,

This invention has as an object the provision for example, bis(amino-t-butyl)biphenyl, in an of synthetic linear polyamides which are soluble alcoholic solution. The resulting salt formed is in readily available volatile solvents such as mixseparated by filtration and the salt heated at tures of alcohols and halogenated methanes. A temperatures of usually ZOO-300 C. in an inert further object is the provision of soluble polyatmosphere or under vacuum for several hours to amides having low water absorption and high obtain the macromolecular fiber-forming polystiffness values. Other objects will appear hereamide. inafter. The more detailed practice of this invention These objects are accomplished by the followis illustrated by the following examples wherein ing invention which comprises synthetic linear parts given are by weight. There are, of course, polyamides containing in the chain recurring many forms of the invention other than these groups of the type: specific embodiments.

, This example describes the preparation and in which R isselected from the class of hydrogen 40 fifi fig f and P and! 15 it a 5 5 f g Essentially equivalent amounts of bis(amino-tg gs g 2 g f 2 55 252 butyl) biphenyl and sebacic acid dissolved in warm i 'zifi andgdiphenylmetgafie sinc ethanol were mixed and the resulting insoluble Ar is ar lene the two free valences belon g'to the salt was separated by filtration The'salt was "nuclei y v a hieaggg ii;: a? evacuateciil, scale}? 1if eaiction ve fiel a or one an onea ours. e 2: gg gz g gzi fizsg gfi f5 reaction vessel was then vented to reduce the in- I ternal pressure to atmospheric and heating was cosity of at least 0.4 and a unit length of at least continued at c for three hours while a slow 7 asdefined inU. S. P; 2071 2'54 and U35. P.

2 130 948 r 5 stream of nitrogen was passed over the surface {F0} practice of this ihvention .(the provb of the melt. The reaction vessel was then evacuatedto about 5 mm. of mercury pressureand sion of polyamides having the desired novel comi ti ti d t C f h 'bination of propertieslat least 50% of the amide ea ng was con nue or seven ours groups in the polyamides should be derived from The clear viscous melt cooled to a tough clear diamines of the, formula manually spinnable solid which had a softening CH3 CH3 temperature on a metal block of about 175 C. I v (I) g and an intrinsic viscosity in m-cresol. of 0.93 Nm-cm- A B: when measured as described in U. S. Patent 2,130,948 and a molecular weight in excess of 3500.

Tensile strength. lbs./sq. in 8000 Film stiffness, M 1b./sq. in. (Tinius- Olsen test) 50% relative humidity 0.30

Wet 0.28 Water absorption .per cent 2.9 Dimensional swelling in water do 0.40

Filments prepared by extrusion of the molten polymer through a suitable orifice were readily drawn to four to five times the'original length, the drawn filaments having a tenacity of about three grams per denier with a break elongation of 16-20%. Filament stiffness (E 10 1b./sq. in.) was 0.70 at 50% relative humidity and 0.69 after soaking in water for twenty-four hours.

In contrast to this polymer the closest homolog known to the art is the polyamide from bis- (p-aminoethyl) -benzene and sebacic acid which is essentially insoluble in the above mentioned solvents and which is less stiff and more water sensitive as shown in the following table.

Filament stiffness, Ex 10-, lb./sq. in.:

50% relative humidity 0.59

Wet 0.43

Water absorption per ce 3.6

Example II a pressure of about 5 mm. of mercury. The clear, 7

viscous melt cooled to a transparent, tough solid which could be manually spun into filaments which were readily cold-drawable. The polymer softened at about 175 C. and was soluble in chloroform. Clear, transparent film were obtained by casting technique.

Example III Example IV This example describes the preparation of the polyamide from bis(amino-t-butyl)bibenzyl and sebacic acid.

The salt prepared from bis(amino-t-butyl)bibenzyl and sebacic acid was heated at 285 C. at atmospheric pressure under nitrogen for one and one-half hours and then for three hours at 285 C. at a pressure of about 5 mm. of mercury. The clear. viscous melt cooled to a tough, transparent solid softening at 150 C. on a metal block. The

polymer could be hot pressed to a clear. tough him and was soluble in chloroform-methanol mixtures.

Example V This example describes the preparation of the olyamine from bis(amino-t-butyl)benzene and sebacic acid.

The salt prepared from bis(amino-t-butyl) benzene and sebacic acid was heated in an evacuated. sealed reaction vessel for three and one-half hours at 210-2l5 C. The reaction vessel was then vented to atmospheric pressure and heating was continued for one hour at 285 C. under an atmosphere of nitrogen. The clear, viscous melt was then heated for six hours at 285 C. under a mercury pressure of about 5 mm. The resulting tough, colorless polyamide was manually spinnable, softened at about C. and was readily soluble in chloroform.

The above examples disclose the preparation of polyamides by the condensation of dibasic acids with bis(beta-amino-alpha-alkyl ethyl) aromatic hydrocarbons. The invention includes within its scope the preparation of interpolyamides in which a minor proportion of the amide groups are derived from amine components other than the specific ones mentioned. To obtain the properties of solubility, stiffness and low water absorption in the polyamide it is preferred that at least 50% of the amide groups be derived from the previously described arylene compounds. Thus, this invention includes such interpolyamides as the following in which the amine component in (A) is present in larger amounts on an equivalent basis than the amine component in (B).

(A) I (B) l bis(Amino-t-butyl)benzene/sc- Caprolactam bacic acid 2 bis(Amino-t-butyDbiphenyl/ Hexamethylenediamine/adipic adipic acid acid 3 bis (Amino-t-butyl) biphcnyl/ Hexamethylencdiamine/adipic adipic acid acid/ca rolactam 4 bis(Amino-t-butyl) biphcnyl/ Hexamet ylenedlamine/adipic sebacic acid acid; and/or hexamethylenediamine/sebacic acid lene with at least a two-fold molecular amount of a terminal methylene C3-C4 alkenyl monoamine having at least one and preferably two hydrogens on the amino nitrogen and having the unsaturation between the beta and gamma carbons in the presence of a polyvalent element halide Friedel-Crafts catalyst such as aluminum chloride. Further details are given in our copending application Serial No. 586,446 filed of even date herewith. The amine-forming reaction is usually carried out in the presence of an inert solvent at temperatures of 20-80 C. and the diamine is separated by treating the reaction mixture with water, separating the solvent and adding an excess of an alkali. Further details of this are disclosed in our copending application filed of even date herewith.

It is preferred that the polyamides be obtained by reacting the above described type of diamine with a dibasic acid having at least three carbons between carboxylic acid groups and preferably less than twenty carbon atoms, for example, adipic acid, pimelic acid, suberic acid, sebacic acid, terephthalic acid, etc. The preferred dibasic acids are adipic and sebaclc acids.

Polyamides obtained by the use of other diamines have not been found to have the novel combination of properties shown by the polyamides of this invention. Thus, polyamides derived from the, at first glance, closely related diamine nmcmonQcmcnmm (cf. U. S. 1?. 2,312,966) are not soluble in such solvents as chloroform or chloroform-mechanol mixtures.

The many advantages in employing solutions of polyamides in which the solvent is readily volatile, cheap and relatively nontoxic are numerous. Thus, films can be obtained by casting of the solutions and fibers by dry spinning. The solvents of the above type are preferred to solvents such as phenol or formic acid which must be employed for polyamides most readily available, e. g., polyhexamethyleneadipamide. The following table illustrates the difference in properties of one of the polyamides of this invention (last item) as compared to prior art polyamides:

tended to be illustrative only. Any modification thereof or variation therefrom which conforms to the spirit of the invention is intended to be included within the scope of the claims.

What is claimed is:

1. A synthetic linear polycarbonamide characterized by an intrinsic viscosity of at least 0.4, solubility in methanol-chloroform mixtures and by a predominance of recurring units of the formula Stiffness Water Softening Solubility in EXl0- lb./sq. in. Polyamide OHCIFC 3:03 Aigsgrgggn, ILoiit,

% R. H. Wet

Polyhexamethylene adipamide 0. 45 0. l7 9. 0 264 Polyhexamethylene sebacamide do 0. 45 0. 28 3. 9 220 Polyhefigmetliylene-adipamide/polyhexamethylenesebacamide/caprolacsoluble 0.10 0.05 10.5

am er ymer. bis(2-Ammoethyl) benzene-sebacic acid polymer insoluble 0.59 0. 43 3. 6 285 is(Aminat-butyl)-biphenyl-sebacic acid polymer soluble 0. 70 0. 69 2. 0-3.0

In the above table the water absorption was measured on undrawn films or filaments while the stiffness was measured on drawn filaments.

The polyamides of this invention are utilized ing a predominance of and at least seven recurring units of the formula .Nncm iicgggmiw ll- WILLIAM KIRK, JR. RICHARD SEYFARTH SCI-IREIBER.

file of this patent:

UNITED STATES PATENTS Number Name Hanford Mar. 2, 1943 Date Certificate of Correction 7 Patent No. 2,464,693. I March 15, 1949.

. WILLIAM KIRK, JRQ, ET AL.

It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 2, line 41, Example 1, for amio read amino; column 3, line 13, for "Filments read Filaments; line 47, for the word film read films; line 48, for technique read techniques; column 4, hne 7, for po1yamine read polyamide;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office,

Signed and sealed this 13th day of September, A. D. 1949.

JOE E. DANIELS,

Assistant Oomxrm'asioner of Patents. 

